src/bin/lttng-sessiond/lttng-sessiond.h

   1 /*
   2  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   3  * Copyright (C) 2013 Raphaël Beamonte <raphael.beamonte@gmail.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 #ifndef _LTT_SESSIOND_H
  10 #define _LTT_SESSIOND_H
  11
  12 #include <urcu.h>
  13 #include <urcu/wfcqueue.h>
  14
  15 #include <common/sessiond-comm/sessiond-comm.h>
  16 #include <common/compat/poll.h>
  17 #include <common/compat/socket.h>
  18 #include <common/uuid.h>
  19
  20 #include "session.h"
  21 #include "ust-app.h"
  22 #include "notification-thread.h"
  23 #include "sessiond-config.h"
  24
  25 /*
  26  * Consumer daemon state which is changed when spawning it, killing it or in
  27  * case of a fatal error.
  28  */
  29 enum consumerd_state {
  30         CONSUMER_STARTED = 1,
  31         CONSUMER_STOPPED = 2,
  32         CONSUMER_ERROR   = 3,
  33 };
  34
  35 /* Unique identifier of a session daemon instance. */
  36 extern lttng_uuid sessiond_uuid;
  37
  38 /*
  39  * This consumer daemon state is used to validate if a client command will be
  40  * able to reach the consumer. If not, the client is informed. For instance,
  41  * doing a "lttng start" when the consumer state is set to ERROR will return an
  42  * error to the client.
  43  *
  44  * The following example shows a possible race condition of this scheme:
  45  *
  46  * consumer thread error happens
  47  *                                    client cmd arrives
  48  *                                    client cmd checks state -> still OK
  49  * consumer thread exit, sets error
  50  *                                    client cmd try to talk to consumer
  51  *                                    ...
  52  *
  53  * However, since the consumer is a different daemon, we have no way of making
  54  * sure the command will reach it safely even with this state flag. This is why
  55  * we consider that up to the state validation during command processing, the
  56  * command is safe. After that, we can not guarantee the correctness of the
  57  * client request vis-a-vis the consumer.
  58  */
  59 extern enum consumerd_state ust_consumerd_state;
  60 extern enum consumerd_state kernel_consumerd_state;
  61
  62 extern const char default_home_dir[],
  63         default_tracing_group[],
  64         default_ust_sock_dir[],
  65         default_global_apps_pipe[];
  66
  67 /* Set in main.c at boot time of the daemon */
  68 extern struct lttng_kernel_tracer_version kernel_tracer_version;
  69 extern struct lttng_kernel_tracer_abi_version kernel_tracer_abi_version;
  70
  71 /* Notification thread handle. */
  72 extern struct notification_thread_handle *notification_thread_handle;
  73
  74 /*
  75  * This contains extra data needed for processing a command received by the
  76  * session daemon from the lttng client.
  77  */
  78 struct command_ctx {
  79         unsigned int lttng_msg_size;
  80         struct ltt_session *session;
  81         struct lttcomm_lttng_msg *llm;
  82         struct lttcomm_session_msg *lsm;
  83         lttng_sock_cred creds;
  84 };
  85
  86 struct ust_command {
  87         int sock;
  88         struct ust_register_msg reg_msg;
  89         struct cds_wfcq_node node;
  90 };
  91
  92 /*
  93  * Queue used to enqueue UST registration request (ust_command) and synchronized
  94  * by a futex with a scheme N wakers / 1 waiters. See futex.c/.h
  95  */
  96 struct ust_cmd_queue {
  97         int32_t futex;
  98         struct cds_wfcq_head head;
  99         struct cds_wfcq_tail tail;
 100 };
 101
 102 /*
 103  * This is the wait queue containing wait nodes during the application
 104  * registration process.
 105  */
 106 struct ust_reg_wait_queue {
 107         unsigned long count;
 108         struct cds_list_head head;
 109 };
 110
 111 /*
 112  * Use by the dispatch registration to queue UST command socket to wait for the
 113  * notify socket.
 114  */
 115 struct ust_reg_wait_node {
 116         struct ust_app *app;
 117         struct cds_list_head head;
 118 };
 119
 120 /*
 121  * Used to notify that a hash table needs to be destroyed by dedicated
 122  * thread. Required by design because we don't want to move destroy
 123  * paths outside of large RCU read-side lock paths, and destroy cannot
 124  * be called by call_rcu thread, because it may hang (waiting for
 125  * call_rcu completion).
 126  */
 127 extern int ht_cleanup_pipe[2];
 128
 129 extern int kernel_poll_pipe[2];
 130
 131 /*
 132  * Populated when the daemon starts with the current page size of the system.
 133  * Set in main() with the current page size.
 134  */
 135 extern long page_size;
 136
 137 /* Application health monitoring */
 138 extern struct health_app *health_sessiond;
 139
 140 extern struct sessiond_config config;
 141
 142 extern int ust_consumerd64_fd, ust_consumerd32_fd;
 143
 144 /* Parent PID for --sig-parent option */
 145 extern pid_t ppid;
 146 /* Internal parent PID use with daemonize. */
 147 extern pid_t child_ppid;
 148
 149 /* Consumer daemon specific control data. */
 150 extern struct consumer_data ustconsumer32_data;
 151 extern struct consumer_data ustconsumer64_data;
 152 extern struct consumer_data kconsumer_data;
 153
 154 int sessiond_init_thread_quit_pipe(void);
 155 int sessiond_check_thread_quit_pipe(int fd, uint32_t events);
 156 int sessiond_wait_for_quit_pipe(int timeout_ms);
 157 int sessiond_notify_quit_pipe(void);
 158 void sessiond_close_quit_pipe(void);
 159
 160 int sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size);
 161 void sessiond_signal_parents(void);
 162
 163 void sessiond_set_client_thread_state(bool running);
 164 void sessiond_wait_client_thread_stopped(void);
 165
 166 void *thread_manage_consumer(void *data);
 167
 168 #endif /* _LTT_SESSIOND_H */